Typical paving machines include a vehicle which moves along the area to be paved carrying a hopper which contains a supply of the asphalt paving material and a screed which lays the asphalt paving material onto the area to be paved in a strip of uniform thickness. The asphalt paving material is heated and is applied when it has a plastic consistency so that it may be easily applied in a layer of uniform thickness. In a repaving operation, the new asphalt material may be laid upon the old surface of the roadway. It has been found that the new asphalt material adheres to the old road surface much better when the old road surface is warm. Poor results are obtained when the new asphalt material is applied upon a cold roadway. For this reason, specific temperature conditions exist under which paving must occur to ensure pavement quality. This limits the length of the paving season and the productivity on days when paving crews must wait for the temperature to rise.
In some places, there are only a few brief months when the weather temperature is sufficient to meet the condition for obtaining good results when paving. It has been found advantageous to mount heating apparatus on the paving machine which heats the road surface prior to depositing the new paving material on the road surface. This heating of the road surface raises the pavement temperature to assure a good bonding between the road surface and the new asphalt material.
Paving machines can be relatively large, cumbersome machines especially when equipped with the hopper, screed and heater. The screed width is adjustable so that it can be retracted for travel from one work site to the other and then fully extended for the paving operation. Since the screed is retractable, it is not a limiting factor in the width of the paving machine.
On the other hand, the width of the heater is ideally at least about equal to the screed width and is a limiting factor because it is not adjustable as is the screed. On some prior paving machines, the heater is vertically adjustable so that it can be moved downwardly for heating the road surface and moved upwardly for transport, but is not horizontally adjustable. Since the heater must heat a strip of the road surface which is at least equal to the width of the maximum extension of the screed, the heater is the widest part of the machine and thus limits the transportability of the paving machine. Examples of pavement heaters on prior paving machines are shown in U.S. Pat. Nos. 4,018,540; 3,361,042; 3,221,617 and 3,055,280. Accordingly, it will be appreciated that it would be highly desirable to provide a heater for a paving machine which does not limit the transportability of the paving machine.